A display device that displays an image usually has optical members disposed therein. The optical members utilize the properties and action of light to impart predetermined optical effects (such as polarization, reflection, selective reflection, light shielding, and wavelength conversion) to light that is emitted toward a display panel that displays an image. For example, in a liquid crystal display device including a liquid crystal panel (a type of display panel) that is capable of displaying an image and a lighting device that illuminates the liquid crystal panel with light, the liquid crystal panel has polarizing plates, provided on a front surface (i.e. an image display surface on which an image is displayed) thereof and a back surface (i.e. a surface opposite to the front surface) thereof, that selectively transmit only light that oscillates in a particular direction. Further, the lighting device, attached to the back side of the liquid crystal panel, has disposed therein optical sheets such as a diffusion sheet, a lens sheet, a prism sheet, a reflection sheet as well as a light guide plate that lets in light emitted from a light source and, while guiding the light through the inside thereof, causes the light to exit toward the display panel in the form of surface light. It should be noted that those of the plate-shaped optical members each of which is formed so that its thickness is sufficiently small with respect to the area of its plate surface are sometimes herein referred to as “optical sheets.”
In recent years, there has been a strong demand for a slimming down of display devices such as mobile terminal devices and TV reception devices. Conventionally, the clearance between constituent members that constitute a display device has been kept in a certain size or larger. However, along with a further slimming down of display devices, constituent members per se are slimmed down, and the clearance between constituent elements is reduced.
When constituent members are stacked in proximity to each other, static electricity generated in the process of manufacture or use exerts a non-negligible effect on the interaction between the adjacent constituent members. A deformation or the like of an optical member due to electrostatic interaction affects the optical action of the optical member to cause deterioration in display quality. In particular, in a case where at least either of the optical members is an optical sheet formed to be comparatively thin and flexible, the optical sheet bends and deforms toward the other optical member and adheres partially to the other optical member. For example, electrostatic attractive force generated between the polarizing plate disposed on the back side of the liquid crystal panel and an optical sheet disposed on a side of the lighting device that is closest to the liquid crystal panel causes the optical sheet to contain air or the like in the space between the optical sheet and an optical member and deform into the shape of a lens to effect interference of light that undesirably creates a pattern of light called a Newton ring.
In view of this, for example, Japanese Unexamined Patent Application Publication No. 2002-258763 discloses a technology, directed to a direct backlight device having linear light sources disposed on a back side of a diffuser, in which the diffuser is provided with a light-shielding pattern that serves as a lighting curtain for increasing the uniformity of light by shielding an intense range of light from the linear light sources and at least a part of the light-shielding pattern is formed by a conductor and connected to the ground.
Japanese Unexamined Patent Application Publication No. 2002-258763 fails to describe a specific configuration for dissipating, out of the display device, electricity guided from the diffuser to the light-shielding pattern. In particular, in a case where the lighting device has a housing made of insulating resin or the like, newly providing a dedicated ground wire and connecting it to each light-shielding pattern makes it impossible to avoid making the liquid crystal display device complex in structure and manufacturing process. Further, although it is desirable that the new ground wire be provided in a frame (i.e. an image non-display section surrounding an image display surface) of the liquid crystal panel, it is not preferable, from the point of view of achieving a narrower frame, to reserve such a space.